Bulletin No. 68 oe EP ETOHTON Mer Gti eo Lee 


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COMMONWEALTH OF PENNSYLVANIA 





DEPARTHENT OF INTERNAL AFFAIRS 
James I. Woodward, Secretary 





BUREAU OF TOPOGRAPHIC AND GEOLOGICAL SURVEY 
George H. Ashley, State Geologist 








LEAD AND ZINC ORES IN LANCASTER COUNTY, PENNSYLVANIA 


By 


Benjamin LeRoy Miller 





Zine and lead minerals have been founc in several places in 
Lancaster County, but the only ones deserving mention are the Pequea 
lead-silver mine and the Bamford zine mine. 


Pequea‘Mine. The Pequéa mine was on Silver Mine Run, near 
Burnt Mills, about 15 miles east of Conestoza. The Iancaster Lead 
Company started work here in 1862 but the venture was unprofitable. 
Six shafts were sunk on four nearly varallel and vertical veins that 
were only 3 to 6 inches wide, The ore was argentiferous galena. One 
piece of ore Weighing 8 pounds is said to have been talen from the 
workings. The veins were mainly in the limestone but near the 
contact with mica schist in which some of them were enclosed. 


The following description of the ore and its occurrence by 
Genth* is the best one known. 


"The galenite of the Pecuea mine in Lancaster County is very 
interesting. The coarse granular variety containing only a small 
quantity of silver occurs in a small irregular vein in the mica slate; 
there is another variety, however, which either alone or associated 
With quartz, feldsvar and mica - a regular granite - forms small 
lenticular, vein-like segregations in the lower Silurian limestone. 

It generally shows a very perfect cubical cleavzge and is highly 
argentiferous, yielding from 250 to 300 ounces of silver per ton. 


"Besides this variety with cubical cleavage there is another 
having a distinct octahedral cleavage into which the first sometimes 
graduates." 





* Genth, F. A.: Mineralogy of Pennsylvania. -2nd Geological Survey of 
Pennsylvania, Report B, pp. 1il-12, Harrisburg, 1874. 





















































































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Bamford Mine. The Bamford Zine mine is 5 miles northwest of 
Lancaster and 1/3 mile north of Bamford. ‘The writer visited the site 
in 1921 but as the openings are now full of water little could be 
learned other than the character of the ore and the country rock from 
the old mine dumps, 


The ore body was discovered during the ilexican War by a man 
digging fence holes, A chemist reported that the ore contained Zinc, 
lead, and traces of silver, ‘The Lancaster Zine Company was organized 
and by 1855 had realized $30,000 from the sale ‘of stock. A plant 
capable of manufacturing one ton of Zine oxide per day was built ata 
cost of $23,000, The mine report of 1855 states that $1,989 was 
realized from the sale of zine oxide. The project failed, 


The mine remained idle until 1872 when Charles Bamford bought the 
property and built an expensive mining and reducing plant. He is said 
to have spent about $300,000 with little returns, and in 1877 closed 
the mine, which then had two openings on different veins. 


In April 1883 the Lehigh Zine and Iron Company leased the mines 
and re-opened them, lack of ore and difficulties with the machinery 


made the veéntare unprofitable and overations ceased in the fall of 
1883, 


In 1900 an Ohio firm secured leases on the mines but apparently 
withdrew without re-opening the old workings. 


Good descriptions of the Bamford mine by Persifor Frazer, Jr., 
and by E, G, Spilsbury are given in Pennsylvania Second Geological 
Survey Report CCC, Geology of Lancaster County, published in 1880. 
From this report the-following information is abstracted. 


The ore is in two bedded veins, and not in’fissure or gash veins. 
These bed-veins are in lower Silurian limestone, near the contact with 
shale, They are conformable to both stratification and dip of the 
limestone, their general course being N 74° B and dip NW 72°. The 
hanging wall of both veins is brecciated, light gray, siliceous 
limestone and the footwall is dark blue or black, less siliceous 
limestone. The gangue is limestone, slightly crystalline in spots 
and much lixe the footwall. 


The ore minerals from the surface to permanent water level at’a 
depth of 16 feet are calamine and cerussite, and below water level, 
the sulphides of zinc and lead, galena, and sphalerite, The galena 
occurs mostly in bunches and little strings along or near the hanging 
wall, and the sphalerite impregnates the whole vein in greater or less 
proportions, averaging 17 to 18 per cent. Specimens of the galena 
may assay from $2 to $2,000 per ton in silver and the difference in 
value be indistinguishable to the eye. The average value in silver 
is about $22 per ton. 


The sphalerite or blende is the bright golden or rosin blende 
and is very pure, 


The veins have been traced on the Bamford property for about + 


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mile. In 1876 both veins had been opened and worxed down to the 
75-foot level, and the south vein had been cut at the 110-foot level. 


The north vein had been mined for 300 feet-alons its course and 
averaged 12 feet wide, It was perfectly barren, however, below the 
50-foot level, 


The south vein, which was the most regular and the richest, had 
been worked out to the 75-foot level, and on a length of over 4.00 
feet, The average width was from 14 "to 18 feet, Although in some 
portions the ore was very rich, still the average amount of azine in 
the vein never exceeded 12 per cent, and no ore was ever pure:enough 
to treat without previous concentration, excepting, of course, the 
surface deposits of calamine. The richest ore occurred about fifty 
feet from the surface, and from there down to 75 feet. At the 110- 
foot level, although the vein was well defined, there was little or 
no ore in it, at any-‘of the points where it had been opened, and what 
a apne ore was in it, appeared in strings, and not disseminated, as 
abDOVE, ; 


The spelter manufactured at Bamford was very pure and acquired 


& good reputation. About 357 tons of speltcr was produced between 
1873 and 1876, 


Future Development. 


So far as known there have been no attempts to re-open the 
Lancaster County lead and zine mines within recent years, When they 
were closed it was the prevailing opinion that it was extremely doubt- 
ful whether they could ever be worked with profit. It is true, 
mining and concentration methods have undergone some change since the 
closing of these operations, but it is still doubtful whether it would 
be advisable for any company to expend further time and money in 
working these deposits, 


Bibliography. 


Parker, Cleaveland, Elementary Treatise on Mineralogy and Geology, 
p. 514, Boston 1816. 


Genth, F. A., Mineralogy of Pennsylvania, Pennsylvania Sccond 
Geological Survey, Report B, pp. ll-12, 1874. 


Prazer, Persifor, Jr,, Geology of Lancaster County, Pennsylvania Second 
Geological Survey, Report OCC, pp. 34, 55-56, 196-203, 1880. 


Roddy, Justin H,., Physical and Industrial Geography cs Lancaster 
County, Pa. De 62, LO LG. 


Roe ae samuel G,, Mineralogy of Pennsylvania: Academy of Natural 
Sciences of Philadelphia, Sp. pub. No, 1; 255 pp. 1922, 


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